Ключевые слова: against, air, asia, asian, background, beijing, boy, breath, care, child, china, chinese, city, concept, danger, dirty, emission, environment, environmental, face, filter, food, harmful, hazard, haze, health, human, male, man, mask, mist, mouth, outdoor, people, person, pm, pollute, polluted, pollution, protect, protection, sick, sky, smog, street, unhealthy, urban, virus, wearing, young,